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Abstract

The crustacean Cherax quadricarinatus (redclaw), a crayfish from Australia that is
widely cultured, was introduced illegally into Puerto Rico in the beginning of 1997. They
escaped from a single culture facility at the headwaters of the Loíza River in 1998
during Hurricane Georges and subsequently were found in the Loíza River and later in
the Lajas Valley, where they had been transferred for experimental purposes. The
Bayamón River (Cidra reservoir), Espíritu Santo River, Lajas Drainage Canal and Loíza
River systems were sampled quarterly for one year, to establish the range within Puerto
Rico’s streams to evaluate the crayfish population and determine its preferred habitat.
The Arecibo, Blanco, La Plata, and Río Piedras rivers were sampled at least once to
determine the presence of redclaw. Five 6-mm mesh cylindrical traps were used to
catch redclaw and other organisms. Mean redclaw catch per unit of effort (CPUE) in 12
hours was 1.85, 1.60, and 1.45 in Loíza, Carite and Cidra reservoirs, respectively; and
1.0, 1.35, and 0.55 in the Lajas Drainage Canal, and Loíza reservoir headwaters
(Gurabo and Loíza Rivers), respectively. No redclaw were captured below dams
(tailwaters) of the Cidra and Loíza reservoirs, and no redclaw were captured in the
Espíritu Santo River system. Positive correlations (species correlation with variable)
were found for Macrobrachium acanthurus/pH (r= 0.651), Macrobrachium faustinum/pH
(r= 0.857), M. acanthurus/DO (r= 0.831), Macrobrachium carcinus/turbidity (r= 0.744);
negative correlations were found for redclaw/DO (r=-0.419), Epilobocera
sinuatifrons/discharge (r=-0.447), E. sinuatifrons/temperature (r=-0.766), redclaw/M.
acanthurus (r=-0.522), redclaw/M. carcinus (r=-484), redclaw/Xiphocaris elongata (r=-
0.463). There were more than 24 aquatic exotic species trapped during the study. Thus, redclaw is established in Puerto Rico. Slow-moving waters, including reservoirs and
canals, and with muddy or silty bottoms were redclaw habitats. Assuming a constant
rate of dispersion of redclaw of 0.5 river systems each year, 5 additional river systems
would become theoretically inhabited by redclaw within the next ten years. Redclaw
cause no evident environmental damage (though specific studies regarding their
potential ecological impact are needed), and are being exploited as a food organism by
an unknown number of local fishermen.